Ducts are commonly used in aircraft, houses and vehicles for heating, ventilating, and cooling by the conveyance, delivery and removal of air. Air ducts are designed for the efficient delivery of air and to ensure acceptable indoor air quality as well as thermal comfort. Ducts can be made out of a variety of materials including metals and fiberglass, but are typically made from galvanized steel or aluminum sheet metal. The standard and most commonly used material in fabricating ductwork is galvanized steel. For insulation purposes, metal ducts can be lined with a fiberglass duct-liner or wrapped externally with a fiberglass blanket. Typically, sheet metal ducts are installed first, and then covered with insulation.
Commercial aircraft have air duct network systems for heating and air conditioning, which convey air to the passenger cabin and the cockpit. A central air supply system can be controlled from the cockpit, which serves to constantly supply fresh air to the passengers and crew. The fresh air can be taken from the aircraft power unit as the so called bleed air, and routed into the interior of the aircraft through a series of ducts and air inlet openings. The bleed air is drawn from the compressor stages of a turbine engine and conducted through the duct network at temperatures of up to 957° F. and pressures of up to 312 psi. The hot fresh air can be cooled and dehumidified and distributed to the various parts of the plane for the comfort of the passengers and crew. Bleed air may also be used for cabin pressurization and wing de-icing.
The construction of ductwork starts by measuring the distance and angles to suit the installation. Ducts can be customized for special shapes either on site or in the shop. The duct parts can be cut or bent if required to obtain different fittings, e.g. elbows and tapers. For the final assembly, the ducts can be connected or bolted together through a series of connectors. The use of connectors, however, may require a large working area for their installation and may result in a rigid ductwork structure. This is not particularly desirable in aircrafts where ease of installation and motion absorption are important.
It would therefore be helpful to provide new devices, systems, and methods for connecting flexible ducts, particularly an anti-rotation duct restraint device and system, and methods for using the device and system for installing, connecting and removing ducts with single hand using a single tool. Accordingly, in one aspect of the invention an anti-rotation duct restraint for connecting flexible ducts includes a flexible cable; a swaged cable end coupled to the cable along an axis of the cable; and a flattened threaded cable end coupled to the cable along the axis of the cable.
In another embodiment of the invention, an anti-rotation duct restraint system for connecting flexible ducts includes a flexible cable; a swaged cable end coupled to the cable along an axis of the cable; a flattened threaded cable end coupled to the cable along the axis of the cable; a washer, wherein the washer fits between the swaged cable end and a first flange of a first flexible duct; a mating metal bushing, wherein the mating metal bushing is adapted to fit over flattened threaded cable end, and wherein the flattened threaded cable end and mating metal bushing, together, fit into a second flange of a second flexible duct; and a nut, wherein the nut can be threaded onto the flattened threaded cable end for connecting the first flexible duct with the second flexible duct.
In yet another embodiment of the invention, a method for connecting flexible ducts using an anti-rotation duct restraint system includes preparing a flexible cable having a swaged cable end coupled to the cable along an axis of the cable, and a flattened threaded cable end coupled to the cable along the axis of the cable; aligning the swaged cable end with a through-hole in a first flange of a first flexible duct, and a washer, wherein the washer fits between the swaged cable end and the first flange of a first flexible duct; aligning the flattened threaded cable end and a mating metal bushing with a through-hole in a second flange of a second flexible duct, wherein the mating metal bushing is adapted to fit over flattened threaded cable end, and wherein the flattened threaded cable end and mating metal bushing, together, fit into the second flange of the second flexible duct; and securing the flattened threaded cable end to the second flange of the second flexible duct using a nut.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.